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The synthesis of metal nanoparticles by ecofriendly and reliable processes is an important aspect in many fields. In this study, octamethoxy resorcin [4] arene tetrahydrazide (OMRTH)-reduced and stabilized silver nanoparticles were synthesized via a simple one-pot method. Synthesized silver nanoparticles were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM) and particle size analyzer (PSA). Furthermore, the application of OMRTH-AgNps as a simple, cost-effective and sensitive fluorescent sensor for rapid detection of cadmium was explored. Under optimum conditions, the fluorescence intensity of OMRTH-AgNps was inversely proportional to the cadmium concentration. Using OMRTH-AgNps as a selective and sensitive fluorescent probe, cadmium can be detected at a minimum concentration level of 10 -8 M in a facile way of fluorescence quenching, i.e., by a ''turn off'' mechanism. The method has been successfully applied for determination of Cd [II] ions in groundwater and industrial effluent wastewater samples.

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Novel Supramolecular fluorescence receptor derived from calix-system i.e. calix[4]resorcinarene bearing dansylchloride as fluorophore was designed and synthesized. The compound was purified by column chromatography and characterized by elemental analysis, NMR and Mass spectroscopy. Tetradansylated calix[4] resorcinarene (TDCR) shows a boat conformation with C(2)v symmetry. The complexation behaviour of metal cations [Ag(I), Cd(II), Co(II), Fe(III), Hg(II), Cu(II), Pb(II), Zn(II), U(VI) (1 × 10(-4) M)] with tetra dansylated calix[4]resorcinarene (1 × 10(-6) M) was studied by spectophotometry and spectrofluorometry. Red shift in the absorption spectra led us to conclude that there is strong complexation Fe(III), Co(II) and Cu(II) with TDCR. These metal cations also produce quenching with red shifts in the emission spectra. The maximum quenching in emission intensity was observed in the case of Fe(III) and its binding constant was also found to be significantly higher than that of Co(II) and Cu(II). Quantum yield of metal complexes of Fe(III) was found to be lower in comparison with Co(II) and Cu(II) complexes. Stern Volmer analysis indicates that the mechanism of fluorescence quenching is either purely dynamic, or purely static.

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